Mechanisms of chromosome banding are investigated. These studies include whole mount electron microscopy of banded chromosomes, studies of the interaction of quinacrine, methylene blue and Hoechst 33258 to DNA and chromatin using circular dichroism, equilibrium dialysis, spectroscopic and fluorescence spectra, and changes in DNA viscosity. Nuclear proteins are also examined by high resolution SDS gel electrophoresis. The relative contribution of structural and contractile proteins to the non-histones will be determined. Individual proteins are isolated for amino acid analysis and peptide mapping. Antibodies will be made to these proteins and used and chromosome banding. Non-histone proteins specific to heterochromatin will be isolated and characterized. Bibliographic references: Comings, D.E.: Mechanisms of chromosome banding, IV. Optical properties of the Giemsa dyes. Chromosoma 50:89- 110, 1975. Comings, D.E. , Kovacs, B.W., Avelino, E. and Harris, D.C.: Mechanisms of chromosome banding V. Quinacrine banding. Chromosoma 50:111-145, 1975.